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For example, a listen server on my desktop (Core i7-3770 w/ 12 GB RAM) used around 600 MB RAM, 14% CPU, and at times accessed the HDD at 1 MB/s when running KF-Doom2-HiRes11. On the same map, the "dedicated" server only used 298 MB RAM, with 0% CPU or HDD activity. In contrast, my old laptop with a Core2 T7200 CPU and 4 GB RAM does nothing but run a "proper" dedicated server. The server's memory footprint is a mere 140 MB on KF-Doom2-HiRes11, with no CPU load, and HDD access only when switching maps. Additionally, it's configured to redirect players to download maps and mutators from my website, circumventing my ISP's 1 Mbps upload cap. That way I could concievably play KF on my desktop while doing an anti-virus scan, join the server on my laptop, and not hurt the experience of other players on the server.
Did that make sense?